@magnetsmangadex True, some inflation is needed as your population grows. It's so that the already-sufficient business owners feel a sense of hurry to make more money and thus cause them to hire more people to make them more money. It's how jobs are created if used correctly.
However, the description of pocket money does say it scales with his level. Even if we don't know the what type of scaling it uses, you can always assume that higher level = more money. If it's a broken exponential, or even multiplicative, scaling, the economy is really fucked if he starts spending his money irresponsibly. Knowing Japan though, he probably wouldn't do anything on that scale anyway.
Even additive is crazy if what he has in his hand is 1 gold. If we can assume 1 gold = 100 silver = 10,000 copper and the regular isekai prices of a couple copper for food, he's a rich boi.
TDLR: He has the ability to break the economy if he's a high level.